Python

Conditionnals

x = 1
if x == 2:
   a = 3
else:
   a = 2
a

2

One-line ternary condition

In languages with a C-syntax, it is possible to write an conditional ternary expression: a = (x == 2) ? 3 : 2. It Python, we can do the same with a more understandable syntax:

a = 3 if x == 2 else 2
a

Easy-to-read conditions

In Python, conditions can be written for normal people.

age = 5
print("young" if 0 < age < 18 else "old")

invitationList = ["Alan", "Bob", "Christine", "Dylan", "Emeline", "Franck"]
me = "John"
if me not in invitationList:
    print("you cannot enter")

Assignments in conditions

According to https://peps.python.org/pep-0572/, it is possible to make an assignment in a condition, like in C. To do that, we use the Walrus operator :=.

a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]
if (n := len(a) > 10):
    print(f"List is too long ({n} elements, expected <= 10)")

No switch, sorry

There is no switch in Python, contrary to C. See https://peps.python.org/pep-3103/

Pattern matching

Here is an example of pattern matching (available in Python 3.10, https://docs.python.org/3/reference/compound_stmts.html#match).

i = 0
match i:
    case 0: print("zero")
    case _: print("non zero")

While loops

x = 0
while x < 10:
    x += 1

For loops

In Python, it is possible to write for loops. They take the form of for i in BLOUP where BLOUP is an iterable. It matches somehow the theory of primitive recursive functions: we know that for loops terminates if the iterable object produces a finite number of elements.

for i in range(10):
    print(i)

Generators

A generator is a special kind of function that contains the keyword yield. It returns an iterator (and thus in Python also an iterable object).

def squares(start, stop):
    for i in range(start, stop):
        yield i * i

for i in squares(1, 6):
    print(i)

1
4
9
16
25

Comparing C and Python